99 lines
2.7 KiB
Plaintext
99 lines
2.7 KiB
Plaintext
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MIPI DSI (Display Serial Interface) busses
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==========================================
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The MIPI Display Serial Interface specifies a serial bus and a protocol for
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communication between a host and up to four peripherals. This document will
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define the syntax used to represent a DSI bus in a device tree.
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This document describes DSI bus-specific properties only or defines existing
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standard properties in the context of the DSI bus.
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Each DSI host provides a DSI bus. The DSI host controller's node contains a
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set of properties that characterize the bus. Child nodes describe individual
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peripherals on that bus.
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The following assumes that only a single peripheral is connected to a DSI
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host. Experience shows that this is true for the large majority of setups.
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DSI host
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--------
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In addition to the standard properties and those defined by the parent bus of
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a DSI host, the following properties apply to a node representing a DSI host.
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Required properties:
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- #address-cells: The number of cells required to represent an address on the
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bus. DSI peripherals are addressed using a 2-bit virtual channel number, so
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a maximum of 4 devices can be addressed on a single bus. Hence the value of
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this property should be 1.
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- #size-cells: Should be 0. There are cases where it makes sense to use a
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different value here. See below.
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DSI peripheral
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--------------
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Peripherals are represented as child nodes of the DSI host's node. Properties
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described here apply to all DSI peripherals, but individual bindings may want
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to define additional, device-specific properties.
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Required properties:
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- reg: The virtual channel number of a DSI peripheral. Must be in the range
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from 0 to 3.
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Some DSI peripherals respond to more than a single virtual channel. In that
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case two alternative representations can be chosen:
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- The reg property can take multiple entries, one for each virtual channel
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that the peripheral responds to.
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- If the virtual channels that a peripheral responds to are consecutive, the
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#size-cells can be set to 1. The first cell of each entry in the reg
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property is the number of the first virtual channel and the second cell is
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the number of consecutive virtual channels.
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Example
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-------
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dsi-host {
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...
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#address-cells = <1>;
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#size-cells = <0>;
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/* peripheral responds to virtual channel 0 */
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peripheral@0 {
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compatible = "...";
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reg = <0>;
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};
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...
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};
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dsi-host {
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...
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#address-cells = <1>;
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#size-cells = <0>;
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/* peripheral responds to virtual channels 0 and 2 */
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peripheral@0 {
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compatible = "...";
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reg = <0, 2>;
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};
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...
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};
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dsi-host {
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...
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#address-cells = <1>;
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#size-cells = <1>;
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/* peripheral responds to virtual channels 1, 2 and 3 */
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peripheral@1 {
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compatible = "...";
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reg = <1 3>;
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};
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...
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};
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